1. Field of the invention
The present invention relates to a semiconductor device in which a sealing film is formed on the surface of a substrate and a method for manufacturing said device. The present invention is applied, for example, to a semiconductor device, which uses the wafer, level chip size package method and to a method for manufacturing said device.
2. Description of Related Art
The wafer level chip size package (WCSP) technique is well known as a semiconductor manufacturing technique. WCSP is a technique in which resin sealing is performed before a dicing process.
In WCSP a large number of integrated circuits is formed on the surface of a wafer, and then insulating films comprising protective films, interlayer films and the like are formed on the surface of the wafer so as to expose the center part of each of the electrode pads of these integrated circuits. Next, rewiring patterns are formed on the surface of the exposed face of each pad and on the surface of the interlayer films and, subsequently, bumps are formed on top of this rewiring pattern. The rewiring pattern electrically connects the electrode pads and bumps. Next, a resin sealing film is formed so as to expose the upper ends of these bumps and then external terminals are formed on the upper ends of the bumps.
By using a WCSP technique it is possible to reduce the size of the package and lower manufacturing costs.
In semiconductor devices in which a WCSP technique is employed, one part of the lower surface of the sealing film is in contact with the rewiring pattern and the other part is in contact with the interlayer film. In order to make it more difficult for the sealing film to become detached, it is desirable to increase the size of the contact area between the sealing film and the interlayer film.
However, in contemporary semiconductor devices there tends to be a large number of external terminals. When the number of external terminals increases, the overall area of the rewiring pattern becomes large so that the contact area between the sealing film and the interlayer film is reduced. Therefore, the greater the number of external terminals, the easier it is for the sealing film to become detached.
In addition, in contemporary semiconductor devices there has been a tendency for the chips to become smaller in size. When the chip becomes smaller in size, the contact area between the sealing film and the interlayer film is reduced so that it becomes easier for the sealing film to become detached.
In order to maintain the reliability of semiconductor devices, it is necessary to make it difficult for the sealing film to become detached from the surface of the chip.
An object of the present invention is to propose a semiconductor device in which it is difficult for the sealing film to become detached, and a method for manufacturing said semiconductor device. In other words, the invention aims to propose a semiconductor device which is highly reliable, and a method of manufacturing such semiconductor devices.
The semiconductor device according to the present invention comprises an electrode pad which is formed on a substrate; a covering film which is formed on the substrate and comprises an opening on top of the electrode pad; a rewiring pattern which is formed on the covering film and makes contact with the electrode pad at the opening; a trench which is formed in the region of the interlayer film where the rewiring pattern is not formed; a bump which is formed on top of the rewiring pattern; and a sealing film which covers the rewriting pattern and the trench, and is formed in such a way that the upper end of the bump is exposed.
The semiconductor device according to the present invention is provided with a trench in the covering film so that the contact area between the covering film and the sealing film is increased and therefore it becomes difficult for the sealing film to become detached.
The method of manufacturing the semiconductor device according to the present invention comprises a process for forming an electrode pad on top of a substrate; a process for forming, on top of the substrate, a covering film which comprises an opening on top of the electrode pad; a process for forming, on top of the covering film, a rewiring pattern which is in contact with the electrode pad at the opening; a process for forming a trench in the region of the covering film where the rewiring pattern is not formed; a process for forming a bump on top of the rewiring pattern; and a process for forming the sealing film which covers the rewiring pattern and the trench, in such a way that the sealing film exposes the upper end of the bump.
The manufacturing method according to the present invention comprises a process for providing a trench in the covering film so that the contact area between the covering film and the sealing film is made larger and therefore it becomes possible to manufacture a semiconductor device in which it is difficult for the sealing film to become detached.